Temperature sensing system with retrograde sensor

ABSTRACT

A temperature sensing system and method for determining a patient&#39;s core body temperature by measuring the temperature of the patient&#39;s blood at a location in a vessel lumen retrograde of an insertion point of a temperature sensor or sensors into the vessel lumen.

This application is a divisional application of U.S. Ser. No.10/217,188, filed Aug. 12, 2002 now U.S. Pat. No. 6,866,638.

BACKGROUND OF THE INVENTION

This invention relates generally to a temperature sensing system, andmore particularly concerns a device in the form of a probe or modifiedprobe having temperature sensors for deployment through an introducersheath placed in a body lumen to allow retrograde delivery of thesensors for the measurement or monitoring of the core body temperature.

Under ordinary circumstances, thermoregulatory mechanisms exist in thehealthy human body to maintain the body at a constant temperature ofabout 37° C. (98.6° F.), a condition sometimes referred to asnormothermia. To maintain normothermia, the body's thermoregulatorymechanisms act to precisely balance the amount of heat generated bymetabolic activity in the body with heat lost to the environment. Forvarious reasons, however, a person may unintentionally develop a bodytemperature that is below normal, a condition known as hypothermia. Inmore recent times, hypothermia has been allowed or even induced forvarious therapeutic purposes.

Accidental hypothermia is generally a dangerous condition that may haveserious medical consequences and may result from various conditions suchas extreme exposure, injury, illness or anesthesia. Measures are usuallytaken to restore normothermia to a patient suffering accidentalhypothermia. Simple methods for treating hypothermia include wrappingthe patient in blankets, administering warm fluids by mouth, andimmersing the patient in a warm water bath. If the hypothermia is nottoo severe, these methods may be helpful. However, if the hypothermia issevere, and especially if the patient is undergoing surgery, suchmethods may be too slow, impractical and ineffective. One cannot wrappatients undergoing surgery in a warming blanket or immerse them in warmwater, or ask severely hypothermic patients that may be unconscious, toswallow enough warm liquid to restore normothermia. Furthermore, whereexternal control over body temperature is desired because the physiciandesires to induce and maintain hypothermia, these methods are generallynot powerful enough to defeat the patient's thermoregulatory responses.For example, if a patient is cooled below the shivering threshold,generally about 35.5° C., the body will shiver and generate metabolicheat that will defeat the attempt to cool the patient to hypothermiclevels. Even if the body's thermoregulatory responses are disabled by,for example, disease or anesthesia, surface cooling or warming methodsare generally not powerful enough to provide control that can keep apatient at a particular temperature. If the patient begins to get toocold or to warm above the target temperature, the surface cooling andwarming methods generally cannot react fast enough and with sufficientprecision to maintain the target temperature.

Partly in response to the inadequacies of surface application of heat,methods have been developed for adding or removing heat to a patient'sbody by internal means. A patient being administered breathing gases,for example a patient under anesthesia, may have the breathing gaseswarmed. This method may be effective but is limited in the amount ofheat that can be administered without injuring the lungs. Similarly, apatient receiving IV fluids may have the fluids warmed. This too may beeffective in the case of mild hypothermia, but the temperature of the IVfluid is limited by the temperature that will be destructive to theblood, generally thought to be about 41° C.-49° C., and by the amount offluid that is acceptable to administer to a patient.

A far more invasive method may be used to add heat to a patient's blood,particularly in the case of heart surgery. Blood is removed from apatient, circulated through a by-pass system, heated or cooled, and thenreintroduced into the patient's body. This by-pass method is both fastand effective in adding or removing heat from a patient's blood, but hasthe disadvantage of involving a very invasive medical procedure whichrequires the use of complex equipment, a team of highly skilledoperators, and is generally only available in a surgical setting,usually where the patient has his or her chest opened by a thorachotomy.It also involves mechanical pumping of blood and channeling the bloodthrough various machines and external lines, all of which are generallyvery destructive of the blood tissue. Because of this, most surgeonsavoid placing a patient on by-pass for greater than 4 hours, and ifcontrol of the patient's temperature is desired for longer than thattime, this method is unavailable.

One method for adding or removing heat from a patient by adding orremoving heat from the patient's blood that does not involve pumping theblood with an external, mechanical pump involves placing a heat exchangecatheter in the patient's bloodstream and exchanging heat through thecatheter. This endovascular temperature management (ETM) technique wasdescribed in U.S. Pat. No. 5,486,208 to Ginsburg, the completedisclosure of which is incorporated herein by reference. One methoddisclosed for doing so includes inserting a catheter having a heatexchange region comprising a balloon into the vasculature of a patientand circulating warm or cold heat exchange fluid through the balloonwhile the balloon is in the bloodstream.

In successful ETM, in addition to fast and precise changes in apatient's body temperature, fast and precise control over a patient'sthermal condition is very desirable. A general apparatus and method ofETM control based on feedback from temperature probes in or on thepatient is disclosed in U.S. Pat. No. 6,149,673 to Ginsburg, thecomplete disclosure of which is incorporated herein by reference. Asimilar method is described in PCT publication WO 00/10494 to RadiantMedical Inc., the complete disclosure of which is also incorporatedherein by reference. In such methods, a signal representing thetemperature of a target tissue, which in whole body ETM may be the corebody temperature, is directed to a controller from a temperature probeinserted on or in the patient, and the controller then controls theexchange of heat between the heat exchange catheter and the patient'sblood flowing past that catheter. That in turn controls the temperatureof the patient. With such a method, precise and rapid control isdependent to a large extent on accurate temperature measurement of thetarget tissue and thus dependent on an accurate temperature probelocated at an appropriate site.

Currently, the patient's temperature may be measured by any one ofseveral generally available temperature probes. These include, forexample, skin temperature probes, oral thermometers, tympanic probesthat may be placed in the ear canal and perhaps even in physical contactwith the ear drum, esophageal probes including nasoesophageal probes,rectal probes, bladder probes, temperature sensors placed on aninsertion sheath, and temperature probes that may be inserted by needledirectly into the target tissue. These may be highly accuratetemperature probes for their purpose. However, when used to provide atemperature signal for ETM, each of these probes suffers fromsignificant shortcomings.

Some probes may not give an accurate temperature of the target tissue.For example, if the target is the core temperature of the patient, askin temperature is generally not an accurate representation of the coretemperature; if cardiac muscle is the target tissue, a bladder probemight not be a sufficiently accurate measure of the temperature of thattissue. This is especially true when used in the context of changingtemperature, for example when hypothermia is being rapidly induced bycooling a normothermic patient.

For example, lowering the heart temperature to 32° C. may be verybeneficial for a heart attack victim, but lowering the temperature to28° C. might lead to dangerous arrhythmias. A rectal temperature probeis generally very slow to respond to temperature changes in the body'score temperature, and thus if the target tissue is the heart, and thecore temperature is being lowered quickly, a controller receiving itstemperature signal from a rectal probe might not receive a temperaturemeasurement that represents the current cardiac temperature and thusmight continue cooling even after the cardiac tissue has reached atarget temperature and the patient's actual cardiac temperature mightdangerously overshoot the target temperature of 32° C. and drop thecardiac temperature below 28° C. In similar manner, probes placed in thebladder also tend to lag core body temperature when that temperature isbeing changed, i.e., when the patient is being cooled or warmed.

Some probes are awkward and too difficult to use. For example, tympanicprobes are difficult to place and tend to fall out of the ear duringuse. Bladder probes are difficult and awkward to place and generallyrequire a slow but constant flow of uring to function accurately. Rectalprobes are inconvenient to use, especially where a sterile surgicalfield is required. A needle probed placed through a hypodermic syringeinto the target tissue may be more accurate and precise but wouldrequire injecting the probe directly into the patient and may alsorequire radioscopic or fluoroscopic confirmation of placement,procedures that are not always readily available. Such a procedure wouldalso entail a risk to the patient and the discomfort of a needle stickinto the target tissue which might be deep within the body.

Where a temperature probe is controlling an ETM procedure and thus is inor on a patient at the same time as an ETM heat exchange catheter, theprobe may be unacceptably influenced by the temperature of the catheterand not accurately reflect the temperature of the target tissue,especially if the probe is located too close to the heat exchangecatheter. Temperature probes or sensors placed on the insertion sheath,for example, tend to be unduly influenced by the temperature of the heatexchange catheter placed through the sheath. When the probe is placed inthe vasculature at a location some distance away from the catheter so asnot to be influenced by the catheter, however, it generally requires asecond needle stick or incision, and may utilize a vascular site on thepatient that is needed by a physician for some other purpose. Forexample, if the ETM catheter is located in the left femoral vein, andthe probe is placed in the right femoral vein, it would require aseparate stick, that is, a puncture of the vessel, for the probe andwould make it difficult for an interventionalist to perform angioplastyfrom either the right or the left femoral artery. A temperature probemight be placed through the same introducer sheath used by an ETM heatexchange catheter to access the central vasculature, but in such a caseit would generally be lying alongside the catheter and be influenced bythe temperature of the catheter. If the heat exchange catheter had acentral working lumen as described in the patents and publicationdescribed above, and was located in a central vein, for example theInferior Vena Cava (IVC), a temperature probe might be passed throughthe working lumen and distal of the catheter to measure the temperaturein the blood. Such a probe would not require a second stick to place itinto the bloodstream; however, in this configuration the temperatureprobe would measure the temperature of the blood soon after it passedover the heat exchange surface and thus might not be an accuratemeasurement of the temperature of a target tissue or organ or apatient's core. In some cases, If the temperature probe is advanced farenough beyond the catheter tip to obtain an accurate measure, it mayneed to be positioned in or near the heart which could have serioushealth repercussions. Such a positioning of the probe would alsogenerally require the use of fluoroscopy or x-ray, procedures which arenot always available or desirable.

There is a need therefore, especially in the context of ETM whichrequires accurate temperature information of a patient's target tissue,for a temperature probe that is not unduly influenced by the temperatureof the heat exchange catheter, is located to accurately reflect changesin the patient's temperature, may be conveniently placed, will notrequire that the patient endure additional punctures or surgicalprocedures, will not usurp other needed surgical or interventionalsites, and can be maintained in place throughout the procedure. Thepresent invention fulfills those needs as well as others.

SUMMARY OF THE INVENTION

Briefly, and in general terms, the present invention is embodied in atemperature sensing system that is configured to position a temperaturesensor in a retrograde position, relative to a distal end of a sheathinserted into a lumen of a body vessel, sufficiently retrograde of thedistal end of the sheath so that the temperature sensor is isolated fromany heating or cooling of the body fluid in the lumen caused by thermalinteraction of the sheath, or a catheter or other device insertedthrough the sheath, with the body fluid. More specifically, variousembodiments of the present invention provide for positioning atemperature sensor retrograde of a sheath or introducer in a manner thatprotects the temperature sensor during insertion into the body lumen andfacilitates withdrawal of the temperature sensor when the sensor isremoved from the body lumen.

In one embodiment, the invention is a temperature sensing cathetersystem for measuring the core body temperature of a patient within abody lumen consisting of a sheath having a proximal end with a proximalopening, a distal end region having a distal opening disposed at adistal tip of the distal region, and a lumen therebetween. The cathetersystem also includes a probe having a proximal region and a distalregion having a distal tip, with at least one temperature sensor locatedat the distal tip region of the probe. The probe also has a bend locatedat the junction between the proximal and distal regions such that theprobe may be bent back on itself with the distal region bent backadjacent the proximal region. When the probe is bent in this manner, theprobe may be advanced bend first through an introducer. The probe isadvanced into the sheath until the distal end region of the probe isadvanced beyond the distal end of the sheath, whereupon the distal endregion of the probe separates from the proximal end region of the probeand springs open. The proximal portion of the probe may then be pulledback through the sheath moving the distal end of the probe including thetemperature sensor to a position in the body lumen retrograde of thesheath.

In keeping with the invention, when the sheath is inserted into the bodylumen, the distal portion of the probe up to the bend is longer than thelength of the sheath that is within the body lumen. Thus when the probesprings open and is pulled back within the sheath, the distal portion ispulled retrograde in the vessel.

The probe comprises a temperature probe which carries at least onetemperature sensor at its distal end. The at least one temperaturesensor may be a thermistor, a thermocouple, or any other temperaturesensing device suitable for insertion into a body lumen.

In one embodiment, the distal tip of the probe has at least twotemperature sensors attached thereto. These at least two temperaturesensors can include thermistors or a combination of a thermistor and athermocouple. A conductor extends to each temperature sensor located onthe distal tip of the probe. Further, the temperature sensors can beprotected by a thermally insulated portion of the temperature probe toprevent the conduction of thermal energy to or from the temperaturesensor in a manner that adversely affects the accurate measurement ofthe temperature of the body fluid by the temperature sensor.

In another embodiment, the invention includes a controller unit forproviding temperature indications and a coupler for coupling at leastone temperature sensor to the controller unit. The coupler is attachedto the proximal end of the catheter sheath and is configured toelectronically couple at the least one temperature sensor to thecontroller unit.

In an alternative embodiment, the temperature sensing catheter system ofthe present invention may include a heat exchange type catheter having aheat exchange region. An insulated section of the temperature probe,positioned between the temperature sensor and the portion of the probethat may be effected by the temperature of the heat exchange catheter,prevents heat conduction along the probe to the sensor from the sheathor the heat exchange catheter.

In another embodiment, the invention further includes a controller unitfor accepting a temperature signal from said probe and using saidtemperature signal to control the heat exchange catheter in such a wayto control the exchange of heat between said heat exchange catheter andthe bloodstream. If more than one sensor is disposed on or in the probe,the redundancy may be used for safety by, for example, checkingtemperature signals from each of the sensors against each other forconsistency.

In yet another embodiment, the invention comprises a temperature sensingsystem for determining the temperature of a target tissue of patient bymeasuring the temperature of body fluid flowing with a body lumen,comprising an introducer sheath having a proximal opening, a distal endregion having a distal opening disposed at a distal tip of the distalend region, and a lumen therebetween, the lumen having a diameter at thedistal opening and a temperature probe having a proximal region and adistal region having a distal tip having at least one temperature sensormounted thereon, the temperature probe configured so that when insertedinto the introducer sheath and advanced into the body fluid flowingwithin the body lumen, the temperature probe is located retrograde ofthe distal end region of the introducer sheath.

In still another embodiment, the invention comprises and apparatus forassisting in locating a temperature probe for measuring the temperatureof a body fluid flowing within a body lumen at a position retrogradefrom a distal opening of a lumen of an introducer embodied in adeployment catheter having a proximal end having a proximal opening anda distal region having a distal opening disposed at a distal tip of thedistal region, and a lumen defined by a wall extending between theproximal opening and the distal opening, the distal region beingexpandable from a compressed state when the distal region is disposedwithin the lumen of the introducer, and also having an expanded statewhen the distal region is advanced beyond the distal opening of theintroducer, the distal region also having a guide tube disposed on aninner surface of the wall, the distal region having a proximal portionhaving an opening extending through the wall of the proximal portion ofthe distal region, the opening providing a pathway between the lumen ofthe deployment catheter and an exterior of the deployment catheter whenthe distal region is in the expanded state, a probe having a proximalregion, a bend region and a distal region, the distal region of theprobe having a distal tip, the distal tip and distal region of the probeextending through the guide tube such that the bend region is disposeddistal of the guide tube and the distal region is disposed proximal ofthe guide tube, and a temperature sensor disposed on the distal tip ofthe probe. The distal end region of the deployment catheter may includesone or more slots to assist in achieving the compressed state.Alternatively, the distal end region may be formed from a flexiblematerial such that the wall of distal end region folds, allowing thedistal end region to achieve the compressed state, and to unfold toachieve the expanded state.

The present invention is also directed to a method of measuring the corebody temperature of a patient. The method includes providing a cathetersystem having a sheath having a proximal end with a proximal opening, adistal end region having a distal opening disposed at a distal tip ofthe distal region, and a lumen therebetween.

The method further includes providing a probe having a proximal regionand a distal region having a distal tip, with at least one temperaturesensor located at the distal tip region of the probe. The probe also hasa bend located at the junction between the proximal and distal regionssuch that the probe may be bent back on itself with the distal regionbent back adjacent the proximal region. When the probe is bent in thismanner, the probe may be advanced bend first through an introducer. Theprobe is advanced into the sheath until the distal end region of theprobe is advanced beyond the distal end of the sheath, whereupon thedistal end region of the probe separates from the proximal end region ofthe probe and they spring apart. The proximal portion of the probe isthen be pulled back through the sheath and the distal region includingthe at least one temperature sensors moves in the vessel retrograde ofthe sheath.

In still another embodiment of the method of the present invention, thedistal tip of the probe includes at least two temperature sensorsattached thereto consisting of thermistors, or a combination of athermistor and a thermocouple. A conductor extends to at least onetemperature sensor located on the distal tip of the probe. Further, thetemperature sensors can be housed in a thermally conductive,electrically insulative material.

Yet another embodiment of the method of the present invention includesproviding a controller unit for providing temperature indications and acoupler for coupling the at least one temperature sensor to thecontroller unit. The coupler is attached to the proximal end of thecatheter sheath and is configured to electronically couple the at leastone temperature sensor to the controller unit. In this embodiment,signals representing the temperature sensed by the at least onetemperature sensor are communicated to the controller unit through thecoupler. If more than one sensor is disposed in or on the probe, themethod may include comparing the signals from each of the sensorsagainst one and other to determine the consistency of the measurements.The controller may then command an appropriate response to anyinconsistent or out of range temperature signals from one or more of thesensors. Such a response may include, but is not limited to, alertingthe operator of the controller that an inconsistency exists, waiting apredetermined period of time and then comparing the signals from thesensors again to determine if the inconsistency was an artifact or areal inconsistency, and/or automatically commanding the controller tomaintain the last temperature for which there is data the controller mayrely on to determine that the measurement was satisfactory.

In another embodiment, the method of measuring the core body temperatureof a patient includes the use of a heat exchange type catheter having aheat exchange region. An insulated section of the temperature probe,positioned between the temperature sensor and the portion of the probethat may be effected by the temperature of the heat exchange catheter,prevents heat conduction along the probe to or from the sensor to orfrom the sheath or the heat exchange catheter.

Other features and advantages of the present invention will become moreapparent from the following detailed description of the invention whentaken in conjunction with the accompanying exemplary drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is schematic of one embodiment of a temperature sensing probeaccording to the present invention showing an introducer sheath insertedpercutaneously into a blood vessel of a patient;

FIG. 2 is a schematic, elevational view of one embodiment of thetemperature sensing probe according to the present invention;

FIG. 2A is a schematic, elevational view of another embodiment of thetemperature sensing probe according to the present invention;

FIG. 3 is a schematic of the temperature sensing probe of FIG. 2inserted into a sheath of the temperature sensing catheter system whilein a doubled-over configuration;

FIG. 4 is a schematic of temperature probe of FIG. 2 showing the distalportion of the probe advanced out the distal end of the sheath;

FIG. 5 is a schematic of the temperature sensing catheter systemdepicting the probe of FIG. 2 within the blood vessel in a retrogradeposition;

FIG. 6 is a schematic depicting the retrograde position of the probe ofFIG. 2 relative to a heat exchange catheter inserted through the sheathinto a vessel lumen;

FIG. 7 is a cross-sectional view of an alternative embodiment of thepresent invention depicting a “J” introducer tube within a sheath toguide a temperature probe into a retrograde position;

FIG. 8 is a cross-sectional view of the embodiment depicted in FIG. 7showing the introducer tube in position within the lumen of a vessel;

FIG. 9 is a cross-sectional view of the embodiment of FIG. 7 showinglocation of a temperature probe and withdrawal of the introducer tube;

FIG. 10 is a further depiction of the embodiment of FIG. 7 showing thetemperature probe located within a vessel and the introducer completelywithdrawn;

FIG. 11 is an alternative embodiment of the present invention showing asheath having a central lumen and a side lumen with a temperature wirein the side lumen;

FIG. 12 is a further depiction of the embodiment of FIG. 11 showing atemperature wire advanced through the side lumen of the sheath to locatethe temperature probe in a retrograde position;

FIG. 13 depicts an alternative embodiment of the present inventionillustrating a sheath having a capture portion located at the distal endof the sheath;

FIG. 14 shows the embodiment of FIG. 13 with a temperature wireextending through the central lumen of the sheath and into a side lumenof the capture portion to locate a temperature probe in a retrogradeposition;

FIG. 15 is a cross-sectional view of a further embodiment of theinvention.

FIG. 16 depicts an alternative embodiment of the present inventionshowing a temperature probe wire having a detachable portion attached tothe wire by a breakaway portion;

FIG. 17 shows the embodiment of FIG. 16 inserted in the lumen of a bloodvessel; and

FIG. 18 shows the embodiment of FIGS. 16 and 17 inserted in a lumen ofthe blood vessel with the detachable portion of the temperature probewire separated from the temperature probe and removed from the vessel;

FIG. 19 is a schematic view showing a temperature probe positionedretrograde of the opening of an introducer sheath in a blood vessel of apatient, the temperature probe connected to a controller and controllingthe delivery of heating or cooling fluid into a patient;

FIG. 20 is a block diagram of a method for positioning a temperatureprobe in a position retrograde of an opening in an introducer sheath togenerate temperature signals that transmitted to a controller which thencontrols the delivery of heating or cooling fluid to a heat exchangedevice located in a patient's blood vessel at a position antegrade ofthe temperature probe in accordance with the generated signals;

FIGS. 21A-21C are partial cross-sectional views of an alternativeembodiment of the present invention including a deployment catheterhaving a collapsible and expandable distal region, the distal regionincluding a port allowing a temperature sensor to be guided into aretrograde position; and

FIGS. 22A-22C are partial cross-sectional views of the embodiment ofFIGS. 21A-21C showing the removal of the temperature sensor from theretrograde position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides apparatus and a method for measuring thecore body temperature within a body lumen of a patient using atemperature sensing probe. In particular, the temperature sensing probeof the invention includes at least one temperature sensor selectivelylocated retrograde of an introducer sheath inserted within a bloodvessel during a medical procedure for measuring the temperature of thefluid flowing through the blood vessel to determine the core bodytemperature of patient. Such retrograde positioning of the temperaturesensor protects the temperature sensor from being affected by anyheating or cooling of the blood caused by the sheath or a catheter orother instrument inserted into the vessel through the introducer sheath.In this manner, the temperature sensing system of the present inventionprovides a system and method for determining and monitoring the coretemperature of a patient so that adjustments to the patient's coretemperature may be made in a controlled manner using a heat exchangecatheter system, or any other system designed to controllably alter thetemperature of body fluids flowing through vessel, and thereby,controllably alter the core temperature of the patient.

In the following detailed description, numerous specific details are setforth in order to provide a more thorough understanding of the presentinvention. However, it will be apparent to those skilled in the art towhich this invention pertains that the present invention may bepracticed without these specific details. In other instances, well-knowndevices, methods, procedures, and individual components have not beendescribed in detail so as not to obscure aspects of the presentinvention.

Referring now to the drawings, wherein like reference numerals designatelike or corresponding elements among the several views, there is shownin FIG. 1 a temperature sensing system 5 according to the presentinvention which has been partially inserted through the patient's skininto a blood vessel 10. Blood flow through the vessel is indicated by aset of flow arrows F. Preferably, the catheter is inserted into arelatively large blood vessel, such as the femoral artery or vein,inferior or superior vena cava, or the jugular vein. These blood vesselsare particularly advantageous because of accessibility within thepatient's body and safe and convenient insertion sites along thosevessels, and supply of relatively large volumes of blood flowingtherethrough. The femoral artery and vein and the jugular vein are alsoadvantageous locations for heat exchange systems in that they provideaccess to relatively long, straight blood vessels and thus may providefor easy placement of heat exchange elements into those vessels. Forexample, the femoral vein is generally 36-42 French (12-14 mm diameter;one millimeter of diameter is 3 French), and thus may accommodate arelatively large diameter catheter without significant obstruction ofblood flow. A heat exchange catheter may be advanced through the femoralvein to place the heat exchange region into the inferior vena cava (IVC)which may be about 25-35 cm long and generally at least 66 French indiameter. Thus a heat exchange region, such as a heat exchange balloonlocated on te portion of the heat exchange catheter located in the IVCmay be very large when expanded (e.g. 25 French) without causing anysignificant obstruction to blood flow. Similarly, the jugular vein mayhave a diameter of about 22 French or slightly more than 7 mm. A heatexchange catheter may be advanced through the jugular vein to place intothe superior vena cava (SVC) as is commonly done with central venouslines. Although the SVC itself is rather short (only about 6 cm) thelength for insertion using this insertion cite is about 15-20 cm, andthe diameter of the vessels 14-20 mm (42-60 Fr.). Accordingly, acatheter suitable for insertion into these vessels can be made quitelarge compared to catheters which are inserted into other, smaller,regions of the vascular system.

With further reference to FIG. 1, there is shown an elongated introducersheath 20 with a proximal end 25 having a proximal opening 30, a distalend region 35 having a distal opening 40 disposed at a distal tip 45 ofthe distal end region 35, and an inner lumen 50 which extends within theintroducer sheath from the proximal end thereof to the distal openinglocated in the distal end of the sheath. The distal end region of thesheath is capable of being percutaneously introduced into a biologicalsite, such as a blood vessel 10, of a patient.

In one embodiment of the present invention as shown in FIG. 1, thetemperature sensing system 5 is used for measuring the core bodytemperature of a patient by measuring the temperature of the blood orother body fluid flowing through the body lumen 10. A probe 60 having aproximal region 65, a distal region 70, a bend 95 between the distal andthe proximal regions, and a distal tip 75, extends longitudinallythrough the lumen of the sheath. As is known in the art, the sheathlumen 50 which receives the probe is sized for receiving variousdiameter guide probes, catheters or other medical devices to suit aparticular application.

Associated with the temperature sensing system 5 is at least onetemperature sensor 80 for determining the temperature of the blood orbody fluid retrograde (in this case upstream) from the inserted portionof the sheath 20 within the blood vessel 10 from which the coretemperature of the patient may be accurately determined. In oneembodiment, the distal tip 75 of the probe 60 has at least onetemperature sensors mounted thereon. In another embodiment, there aretwo or more temperature sensors mounted on the distal tip 75 of theprobe. In yet another embodiment, a plurality of temperature sensors maybe mounted along distal region 70 of the probe 60.

The temperature sensor or sensors mounted on the probe 60 may bethermistors, thermocouples or some other device suitably sized andconfigured to measure the temperature of the blood or body fluid flowingthrough the lumen of vessel 10. Alternatively, the type of sensor may bemixed, that is, for example, one sensor may be a thermistor and onesensor may be a thermocouple, where there are two or more temperaturesensors mounted on probe 60. Each temperature sensor may provide atemperature signal to a controller (not shown) which is indicative ofthe temperature of the distal tip at that sensor. The temperature signalfrom the temperature sensor or sensors is transmitted to the controllerover a conductor or lead. The conductor or lead may be an insulated wireformed from materials that are biocompatible yet resist degradation bybody fluids or blood.

Preferably, the temperature sensing system 5 of the present inventionfurther includes a coupler 521 for coupling at least one temperaturesensor 80 to a cable 522 in electrical communication with the controller535. The coupler is attached to the proximal end 530 of the conductorand is configured to electronically couple the conductors or leads fromthe temperature sensor or sensors to a cable or other means so as toconnect the temperature sensors to the controller unit. In this manner,signals generated by the temperature sensor or sensors are communicatedto the controller, where they may be used as input for a microprocessorbased controller. The microprocessor based controller monitors thetemperature signals and controls the circulation rate and temperature ofthe fluid flowing through a heat exchange catheter to warm or cool bloodflowing through the blood vessel to alter or maintain the temperature ofa target tissue, or the core temperature of the patient. For example,when the controller determines from the temperature signals that thetemperature of the blood upstream of the heat exchange catheter is toohigh, the controller causes an increased flow of cooling fluid, or adecrease in the temperature of the cooling fluid, or bothsimultaneously, to provide additional cooling to the blood flowing pastthe heat exchange region of the heat exchange catheter. The controllermonitors the temperature signals and may continually adjust fluidtemperature or flow rate, or both simultaneously, in response to thosesignals to reach the desired blood temperature. The monitoring andcontrolling functions of the microprocessor based controller may usevarious algorithms so that the desired temperature is reached, andmaintained, with as little over or undershoot as possible. Similarly,the same system is responsive to temperature signals indicating that theblood temperature is too low so as to increase the temperature of theblood. While a control system utilizing a microprocessor is described,it will be understood that analog systems may also be used to obtain thesame temperature control in response to the temperature signals providedby the temperature sensors located at a position retrograde of the heatexchange catheter.

With further reference to FIG. 1, the temperature sensing system 5 of anembodiment of the present invention includes an insulator sleeve 85which may house the temperature sensors 80 therein or may be locatedbetween sensors and the portion of the probe shaft 71 adjacent theintroducer sheath when the probe is inserted (see FIG. 5). The insulatorsleeve is made of a biocompatible material that is sufficientlyresistant to degradation resulting from contact with blood or other bodyfluid and which is suitably insulative to prevent thermal energy frombeing conducted along the probe to the temperature sensor. Thisembodiment is advantageous in that it assists in isolating thetemperature sensor to improve accuracy of the measurement of thetemperature of the body fluid in which the temperature sensor isimmersed. Because the insulator sleeve is thermally insulating, thesensors located within the sleeve may be selectively potted with athermally conducting material to ensure that the sensors are in thermalcontact with the blood or fluid stream in which the sensors areimmersed.

FIG. 2 illustrates a schematic, elevational view of one embodiment ofthe probe 60 in accordance with the present invention. An intermediateportion 90 of the probe 60 has a bend 95 formed therein such that theprobe assumes a doubled-over configuration while being inserted into theproximal opening 30 of the sheath 20 (FIG. 3).

FIG. 2A illustrates another embodiment of the present invention. In thisembodiment, wire probe 60 a has a proximal region 65 a, a distal region70 a, a bend 95 a between the distal and the proximal regions, and adistal tip 75 a. At least one temperature sensor 80 a is disposed, thatis, mounted to, the distal tip 75 a. The proximal region 65 a and distalregion 70 a of the wire probe have a diameter that is substantiallyconstant diameter along the entire length of the wire probe.

FIG. 3 illustrates the sheath 20 partially inserted into the body lumen10 of the patient. The probe 60 is first introduced into the proximalopening 30 of the sheath 20 and then advanced through the inner lumen 50of the sheath. As shown in FIG. 3, the probe has a bend 95 locatedadjacent to the beginning of the distal end region 70 such that when theprobe is inserted in the lumen of the sheath, the probe bends back uponitself and the bend in the probe is the leading portion of the probe asit is advanced through the introducer sheath.

Typically, as shown in FIG. 4, the distal region 70 of the probe 60 upto the bend 95 has a length 110 that is longer than the length 112 ofthe portion of the sheath inserted within the body lumen. The length ofthe probe 60 from proximal end 105 to the bend 95 is generally longerthan the length of probe 60 from bend 95 to distal tip of probe 60. Itshould be appreciated that the length of the probe can vary depending onfactors such as the size of the catheter used and the type of medicalapplication employed so as to ensure that the temperature sensor orsensors are positioned far enough retrograde of the sheath to ensureaccurate measurement of the temperature of fluid flowing through bodylumen 10, free of any influence resulting from proximity to the sheathor any other catheters or instrumentation also inserted into the bodylumen through the sheath.

The distal region 35 of the probe 60 separates from the proximal region65 of the probe and springs open from its doubled-over configurationwhen the distal tip with temperature sensor 80 exits the distal opening40 of the distal tip 45 of the sheath. FIG. 5 illustrates placement ofthe distal end region 75 of the probe and temperature sensor 80 in aretrograde position retrograde of the sheath within the blood vessel.

In FIG. 6, a temperature sensing system 110 in accordance with thepresent invention is depicted along with a heat exchange catheter 112having a heat exchange region 115 disposed on a distal end of thecatheter 112 inserted into the vessel 10 through a catheter sheath 20.The distal end of the catheter 112 is typically advanced through thelumen of sheath 20 and into vessel 10 until the heat exchange region 115of the catheter 112 is positioned at a desired location within vessel10.

A typical heat exchange catheter 112 employs a fluid flowing throughlumens in the heat exchange catheter to provide thermal energy to orremove thermal energy from the heat exchange region 115 of the catheterattached to the distal portion of a catheter shaft 113. Heat exchangeregion 115 is typically configured to exchange thermal energy with theblood or body fluid flowing past heat exchange region 115 so as to raiseor lower the temperature of the blood or body fluid. An example of aheat exchange catheter may be found in publication WO 01/58397 A1entitled Multiple Lumen Heat Exchange Catheter, the entire disclosure ofwhich is incorporated herein by reference.

Although heat exchange region 115 is depicted in FIG. 6 as a balloon inwhich heat exchange fluid is circulated into and out of, heat exchangeregion 115 may take different forms. The shape, structure andconfiguration of the heat exchange region is dependent on the needs ofthe particular procedure or vessel in which the heat exchange catheteris placed, and any configuration may be used so long as the size,profile and function of heat exchange region 115 are such that the heatexchange region 115 may be advanced through the vascular system andpositioned where desired without inappropriately interfering with theflow of blood or fluid through the vessel.

It should be appreciated that the fluid flowing though the catheter willaffect the temperature of the catheter shaft and the temperature of thesheath. The shaft, the sheath and the heat exchange region will eachaffect the temperature of the blood as it flows downstream, so that asensor placed in that portion of the bloodstream will not detect atemperature that accurately and reliably represents the core bodytemperature of the patient. The temperature sensing system of thepresent invention, however, enables the positioning of a temperaturesensor retrograde of the sheath, heat exchange catheter shaft and heatexchange region 115 to minimize if not eliminate the effect of thethermal energy being transferred by the heat exchange catheter on thetemperature sensor. In this manner, the temperature sensor system of thepresent invention enables accurate determination of blood or body fluidtemperature, and subsequent interpolation to determine the coretemperature of the patient.

The temperature sensing system of the present invention may furtherinclude a control unit (FIG. 19) which generally controls a heating orcooling device adapted to provide warming or cooling fluids to the heatexchange catheter. The controller controls the heater/cooler in responseto temperature signals received from the temperature sensor or sensorsdeployed in the vessel in order to control the temperature of the heatexchange region 115 at a desired temperature to heat, cool or maintainthe desired temperature of the target tissue or whole body temperatureof a patient.

The present invention also provides a method for determining a patient'score body temperature by measuring the temperature of the patient'sblood or body fluid using a temperature sensor or sensors disposed witha body lumen 10 retrograde of an inserted sheath 20. The method consistsof providing a sheath 20 of the type described in connection withFIG. 1. The sheath is first positioned with its distal opening 40 withinthe body lumen 10 of the patient. The method further includes providinga probe 60 having a proximal region 65, a distal region 70, and a distaltip 75, which extends longitudinally through the lumen of the sheath(FIG. 3). At least one temperature sensor 80 is attached to the probe'sdistal tip.

As shown in FIG. 3, the sheath 20 is inserted percutaneously into thebody lumen 10 of the patient. The probe 60 is first introduced into theproximal opening 30 at the proximal end 25 of the sheath 20. The probe60 has a bend 95 located adjacent to the beginning of the distal endregion 70 such that when the probe is advanced through the lumen 50 ofthe sheath, the probe bends back upon itself so that the distal region70 of the probe is adjacent the proximal region of the probe forming adoubled-over configuration. The probe 60 is then advanced longitudinallythrough the lumen 50 of the sheath 20 until the temperature sensor orsensors 80 are advanced beyond the distal opening 40 at the distal end55 of the sheath, at which point the distal end region of the probe 70separates from the proximal end region of the probe and springs open, asshown in FIG. 4.

With further reference to FIG. 4, the distal region 70 of the probe 60up to the bend 95 is of a length that is longer than the length of theportion of the sheath 20 that is inserted within the body lumen 10.Following the passage of the distal region of the probe from the distalopening 40 at the distal tip 45 of the sheath 20 and into the vessel 10,the distal region of the probe is navigated in a retrograde directionalong the sheath to position the sensor or sensors retrograde of thesheath within the body lumen (FIG. 5). The temperature of the flowingbody fluid, e.g. blood, is then measured by the retrograde sensor orsensors to generate a temperature signal representative of thetemperature of the target tissue, e.g. the core body temperature or thetemperature of the cardiac tissue.

This temperature signal may then be transmitted to a controller 535(FIG. 19), which, in response to said temperature signal controls a heatexchanger such as a heat exchange balloon 507 located on a heat exchangecatheter 505 in the patient's vasculature, such as in the femoral artery510. This in turn may control the temperature of the target tissue, forexample the core body temperature of a patient.

Referring now to FIG. 7, an alternative embodiment of the presentinvention including a method for introduction of a temperature probe toa position distal and retrograde from the opening of a sheath ispresented. In this embodiment, sheath 205 is inserted into vessel 200 ina manner well-known to those skilled in the art. Once sheath 205 hasbeen inserted into vessel 200, an introducer tube 210 may be insertedinto the proximal opening of the sheath 205 and advanced through thelumen of sheath 205. The introducer 210 may be formed from anappropriately biocompatible material that is stiff in some portions ofthe introducer, but flexible at the distal end of the introducer. Inthis manner the introducer tube may be formed such that the distal endof the introducer 210 has a flexible “J” shaped construction that allowsthe introducer 210 to be inserted into advanced through the lumen ofsheath 205, the flexible “J” shaped distal end of the introducerconforming to the configuration of the walls of the sheath, until thedistal end of introducer 210 is advanced beyond the distal end of sheath205. As shown in FIG. 8, once the distal end of introducer 210 hasadvanced beyond the distal opening of sheath 205, the retainedflexibility of the “J”shaped” introducer 210 causes the distal end ofintroducer 210 to return to its original shape, springing into a “J”shaped tube.

As shown in FIG. 8, once introducer 210 has returned to its original “J”shape, the distal opening of introducer 210 now points in a directionupstream, or retrograde, of the blood flowing though vessel 200. Atemperature sensing probe, for example, in the form of a steerable wire215 having a temperature sensor 220 mounted on the distal end thereofmay then be advanced through the lumen of introducer 210 out through thedistal opening of introducer 210. The “J” shape of introducer 210directs the distal end of wire 215 having temperature sensor 220 mountedthereon in a retrograde direction within vessel 200, allowingtemperature sensor 220 to be advanced and navigated to a locationretrograde of the sheath 205 relative to the blood flow in vessel 200.

Once temperature sensor 220 has been positioned at the desired locationwithin vessel 200, introducer 210 may be pulled back through the lumenof sheath 205. As introducer 200 is pulled back within sheath 205, theflexible walls of the distal portion of the introducer 210 allow the “J”shaped distal end of introducer 210 to straighten so that introducer 210may be pulled back within the lumen of sheath 205, leaving temperaturesensor 220 positioned within vessel 200 as shown in FIG. 10. Introducer210 will typically be pulled back through the lumen of sheath 205 untilintroducer 210 is pulled completely out of sheath 205 since the lumen ofsheath 205 will typically be needed to be relatively free of obstructionso that additional catheters, may be advanced through the lumen of thesheath into vessel 200, such as a heat exchange catheter describedabove. In most cases, although not all, introducer 210 will becompletely removed from sheath 205, as shown in FIG. 10, so that sheath20 will be free from any obstruction that may impeded insertion ofcatheters or other devices into the vessel through sheath 205.

When the procedure is completed, temperature sensor 220 may be removedfrom the lumen of vessel 200 by pulling wire 215 backward out of thesheath until the temperature sensor is drawn within the lumen of sheath205 and then removed from the body. The wire will generally be softenough to simply withdraw through the introducer. On rare occasions,however, it may be beneficial to protect the vasculature of the patientfrom any undesirable affects that may be caused by simply pulling wire215 from the body. In theses cases, introducer 210 may again be advancedover wire 215 through the lumen of sheath 205 until the distal end ofintroducer 210 returns to its “J” shape, as depicted in FIG. 8. Onceintroducer 210 has been advanced to this position, wire 215 may bepulled backwards through the lumen of introducer 210 which will guidewire 215 and temperature sensor 220 as they are pulled towards thedistal opening of the distal end of introducer 210. In this manner, the“J” shape of introducer 210 allows for improved guidance of wire 215 andtemperature sensor 220 as they are pulled from the body at thecompletion of the procedure.

As described previously, introducer 210 will typically be completelyremoved from the central lumen of sheath 205 to enable the insertion ofother catheters through sheath 205 into the blood vessel 200. In oneembodiment, introducer 210 may be formed as a removable sleeve insidethe sheath 205 which can be withdrawn and peeled away from the wire 215.In this embodiment, the outer diameter of the introducer 210 may be onlyslightly less than the inner diameter of the lumen of sheath 205. Whenintroducer 210 is pulled back into the lumen of sheath 205, introducer210 may be likened to a lining of sheath 205. Since the inner lumen ofintroducer 210 is only slightly less than the inner lumen of sheath 205,additional catheters, such as a heat exchange catheter, may be advancedthrough the central lumen of introducer 210 into vessel 200.

In yet another embodiment, introducer 210 may include both a centrallumen and a second, smaller, lumen. A stiffening mandrel may be insertedthrough the second smaller lumen and used to straighten the distal “J”shaped end of introducer tube 210 so that it may be pulled back throughthe distal opening of the central lumen of sheath 205. In still anotherembodiment, introducer 210 may be flexible enough so that simplyinserting another catheter, such as a heat exchange catheter, which may,although not necessarily, include a stiffening guide wire, may besufficient to straighten introducer 210. Keeping in mind that thecatheter needs to be atraumatic to a patient's vasculature, theintroducer 210 must be sufficiently flexible relative to the catheter sothat the catheter can straighten the “J” shape without being so stiff asto be traumatic to the vessel.

FIGS. 11 and 12 depict another alternative embodiment of the presentinvention. In this embodiment, a sheath 250 has a central lumen 255 andsmaller side lumen 260. A temperature probe wire 275 may be inserted inthe proximal opening of side lumen 260 and advanced therein. Temperatureprobe wire 275 may be formed from a material having a memory so that thematerial will tend to return to an initial shape after the probe wire isdeformed or its configuration changed, such as when it is inserted intothe lumen of a sheath, and then is released from the constraints, suchas when it is advanced out of the sheath. The probe wire 275 may, forexample, include a bend located at a position proximal to the distal endof wire 275 such that when wire 275 is fully extended, a temperaturesensor 280 mounted on the distal end of wire 275 will be positioned in aretrograde position relative to the location of the bend in wire 275.Wire 275, however, is sufficiently flexible so that when the distal endof wire 275 and temperature sensor 280 is inserted into the proximal endof side lumen 260, wire 275 may be threaded through lumen 260 in such amanner that the lumen 260 causes the bend in wire 275 to straighten outsufficiently to allow wire 275 to be advanced through lumen 260. Anopening 265 is located along the length of side lumen 260. Additionally,side lumen 260 is blocked by a termination or end wall portion 270. Wallportion 270 is curved in such a manner so that as wire 275 is threadedthrough lumen 260, the distal end of wire 275 and the temperature sensor280 are directed through opening 265. To further assist in theretrograde placement, the portion of the wall adjacent opening 262 maybe in the form of a ramp 270′ that directs the wire retrograde when itis advanced through the opening.

Once the distal end of wire 275, including temperature sensor 280, isdirected through opening 265 a sufficient distance, the bend in wire 275and the flexible memory of wire 275 cause the distal end of wire 275 tocurve around so that further advancement of wire 275 in direction A, asshown in FIG. 12, results in the temperature sensor mounted on thedistal end of wire 275 moving into the lumen of a vessel in a retrogradefashion. Further advancement of wire 275 will result in the distal endof wire 275 and temperature sensor 280 moving further in the directionopposite to direction A to locate the temperature sensor proximal toopening 265. This structure allows retrograde positioning of thetemperature sensor 280 while leaving the sensor lumen 255 of sheath 250open so that it can be used for the advancement of other catheters, suchas a heat exchange catheter as described above. When the procedure iscompleted and sheath 250 is to be removed from the lumen of the vessel,wire 275 may be pulled back through side lumen 260 in a directionopposite to direction A as shown in FIG. 12. Pulling wire 275 back in adirection opposite to direction A results in the distal end of wire 275moving towards the distal end of sheath 250, where it is drawn backthrough opening 265 into side lumen 260.

Alternatively, the embodiments depicted in FIGS. 11 and 12 may be usedin conjunction with a temperature probe wire 260 that does not have abend formed in it prior to insertion through lumen 260. Wire 260 may beformed a material that is soft and flexible enough to be deflectedand/or deformed by ramp 271 and wall 270 so that advancement of the wirethrough lumen results in retrograde position of the temperature sensoror sensors 280.

Further embodiments of the present invention are depicted in FIGS.13-15. As illustrated in FIGS. 13 and 14, a sheath 300 having a centrallumen 302 and a distal end 305 is formed to include a capture tube 310.Capture tube 310 may be formed by including an additional lumen eitherintegrally formed with sheath 300 or formed as a separate lumen and thenattached to the distal end of sheath 300. Capture tube 310 has a centerlumen 312 of a sufficient diameter to receive a temperature probe wire315 having a temperature sensor 325 mounted to the distal end thereof.Capture tube 310 also includes a proximal opening 330 and a distalopening 320.

In use, sheath 305 is inserted into the lumen of a blood vessel withtemperature wire 315 extending through central lumen 302. Temperaturewire 315 is formed such that it includes a bend at a selected locationalong the length of wire 315 such that the distal end of wire 315 andtemperature sensor 325 attached thereto extend in a retrograde fashionalong the length of wire 315. The distal end of wire 315, includingtemperature sensor 325, are inserted through the distal opening 320 ofcapture tube 310 and extend through the central lumen 312 such thatduring insertion of the sleeve 305 into a body lumen or vessel thetemperature sensor 325 may be disposed within lumen 312 just distal toproximal opening 330 of capture tube 310. In this manner, thetemperature sensor may be protected during insertion of the sheath 300through the skin of the patient and into the vessel.

Once the sheath is in position within the vessel, the wire 315 may bepulled in direction A, as shown in FIG. 14, to move the distal end ofwire 315 and temperature sensor 325 in the direction indicated bydirection A to position the temperature sensor 325 to a locationretrograde relative to the distal end of the introducer sheath. Whenwithdrawal of sheath 305 from the vessel lumen is desired, wire 315 isadvanced in a direction opposite to direction A, moving temperaturesensor 325 back within proximal opening 330 of capture tube 310. In oneembodiment, a stop 321 is disposed on the wire just proximal of thetemperature sensor may stop the further movement of the wire once it hasbeen adequately withdrawn to bring the temperature sensor into thecapture tube. The opening of the capture tube at 320 may have a smallerdiameter than the diameter of the stop, and further movement of the wirewill not be possible once the probe has been fully retracted. Since thisaction will take place in the patient's vessel and out of the sight ofthe physician, this will also provide a tactile signal that the sensoris properly placed. Once the temperature sensor 325 is completely withinlumen 312 of capture tube 310, sheath 300 may be withdrawn from thevessel and through the skin. This embodiment of the present inventionallows withdrawal of sheath 305 without snagging the distal end of wire315 and temperature sensor 325 on the vascular anatomy or other tissueof the patient. The stop 271 may be formed from any suitablebiocompatible material and is positioned on the wire 315 as desired toensure both proper advancement and retraction of the temperature sensor325. The stop 271 may be either fixed in position, or it may beadjustable to vary the length of the distal end of wire 315 as needed.

An alternative embodiment of the invention illustrated in FIGS. 13 and14 is shown in FIG. 15. In the embodiment of FIG. 15, wire 315 does notextend through lumen 302 of sheath 305. Rather, wire 315 is mountedentirely external to sheath 300, except for a portion of wire 315 thatis inserted through the distal opening 320 of capture tube 310 andextends through lumen 312. As is readily ascertained, temperature sensor325 is located within lumen 312 of capture tube 310 during insertion andwithdrawal of sheath 300 from a patient's body. When sheath 300 issuitably located within the lumen of a blood vessel, wire 315 may beadvanced or withdrawn as necessary to locate temperature sensor 325within the vessel as desired. Although not shown in FIG. 15, a stop maybe mounted on wire 315 as described above with reference to FIG. 13, anddistal opening 320 may be sized to have a diameter larger than thediameter of wire 315 but smaller than a diameter of the stop, so thatthe stop interacts with the distal opening 320 to limit the length ofwire 315 that may be withdrawn into lumen 312.

FIGS. 16-18 depict still another embodiment of the present inventionproviding for positioning a temperature sensor within a vessel in alocation retrograde relative to the direction of the sheath. In thisembodiment, a sheath 350 having a distal opening 360, a proximal opening365, and a central lumen 355 extending therebetween, may have atemperature wire 370 inserted through the proximal opening 365 andextending through lumen 355 and out distal opening 360. Temperature wire370 has a proximal end 380 and distal end 385. Temperature wire 370 hasa proximal end 380 and a distal end 385. Temperature sensor 375 ismounted at distal end 285. Wire 370 further has a detachable portion 390which has a first end 395 and a second end 400. Detachable portion 390of wire 370 is attached to the distal end 385 of wire 370 by way of abreak apart section 405.

Break apart section 405 may be attached directly to temperature sensor385, or it may be otherwise attached to distal end 375 of wire 370.Break apart section 405 may be biodegradable, that is, for example,blood soluble, or it may be formed from any biocompatible material thatis sufficiently weak and may be easily pulled apart. For example,holding proximal end 380 of wire 370 in a stationary position andattempting to withdraw second end 400 of detachable portion 390 in anoutward direction may to apply sufficient tension across break apartsection 405 to cause break apart section 405 to separate from distal end375 of wire 370.

FIGS. 17 and 18 illustrate the embodiment depicted in FIG. 16 disposedwithin a blood vessel. As shown in FIG. 17, sheath 350 is insertedthrough skin 420 through various epidermal and muscle layers 425 andthrough vessel wall 430 into lumen 435 of blood vessel 432. When sheath350 is inserted through skin 420 into lumen 435, wire 380 is positionedsuch that temperature probe 385 is protected within the lumen 355 ofsheath 350. Once sheath 350 is satisfactorily inserted within lumen 435,wire 370 may be advanced through lumen 355 of sheath 350 while the end400 of disposable portion 390 is withdrawn from the wound. Thisadvancement and withdrawal of wire 370 and detachable portion 390results in moving distal end 375 of wire 370 through the distal openingof sheath 350 around the edge of sheath 350 and pulls the temperaturesensor 385 along the outer wall of sheath 350 to a desired locationretrograde of the distal opening of sheath 350.

Once temperature sensor 385 is positioned in the desired locationretrograde of the distal end 360 of sheath 350, force may be applied toend 400 of detachable portion 390 to cause breakaway portion 405 to pullaway from distal end 375 of wire 370, thus separating detachable portion390 from wire 370. When breakaway portion 405 separates, detachableportion 390 may be pulled until the entire length of detachable portion390 is withdrawn from the patient's body, leaving temperature sensor 385in the desired location within lumen 435 of vessel 432. In thisembodiment, wire 370 may be sized such that there is sufficient spacewithin lumen 355 of sheath 350 to allow advancement and retraction ofother catheters, such as a heat exchange catheter as described above,though lumen 355. When the procedure is completed and sheath 350 isabout to be withdrawn from lumen 435 of vessel 432, force may be appliedto end 380 of wire 370 to withdraw wire 370 from sheath 350, causingdistal end 375 to enter distal opening 360 of central lumen 355 of thesheath and then be withdrawn from the patient's vessel.

FIG. 19 depicts a heat exchange system utilizing a heat exchangecatheter 505 having a heat exchange region, here depicted as a balloon507, inserted in a femoral vein 510 of a patient's leg 515. The heatexchange catheter 505 is inserted through sheath 520 into vein 510.Temperature probe 525, in accordance with aspects of the presentinvention described above, is also inserted through sheath 520 in such amanner as to position temperature sensor or sensors 520 at a locationretrograde of the distal opening of sheath 520 and heat exchange balloon507. A conductor 530 electrically connects temperature sensor or sensors525 with controller 535. Conductor 530 conducts electrical signalsgenerated by temperature sensor or sensors 525 to controller 535, inresponse to which controller 535 controls the temperature or rate offlow, or both, of heat exchange fluid circulating through balloon 507through fluid input conduit 540 and fluid return conduit 545.

FIG. 20 is a block diagram depicting a method for positioning a heatexchange catheter and a temperature probe into the vasculature of apatient to alter or maintain the temperature of a target tissue or thebody core of the patient. In box 550, an introducer sheath is insertedthrough the tissue of a patient's body and into the lumen of a selectedportion of the vasculature of the patient. A temperature probe havingtemperature sensors disposed on a distal end of the temperature probe isinserted through the introducer sheath and positioned in the lumen ofthe patient's vasculature at a location retrograde of the distal openingof the introducer sheath in box 555.

In box 560, a heat exchange catheter having a heat exchange region isinserted through the introducer sheath and advanced through thepatient's vasculature until the heat exchange region is in a desiredposition within the vasculature downstream of the distal opening of theintroducer sheath. The input and return fluid lines of the heat exchangecatheter are connected to a heat exchanger and pump that is controlledby a controller, which may be, but not necessarily, microprocessorbased. Conductors of the temperature probe in electrical communicationwith the sensor or sensors of the probe are also placed in electricalcommunication with controller. This connection may be a hard wiredconnection, or alternatively, the temperature sensors may communicatewith the controller using wireless means, such as radio frequency, infrared, blue tooth, or other scheme capable of communicating signalsrepresenting the temperature of the fluid sensed by the temperaturesensors from the sensors to the controller.

Signals generated by the temperature sensors (box 565) are communicatedto the controller in box 570. In box 575, the controller, in response tothe signals communicated from the sensor or sensors, adjusts the rate offlow of heat exchange fluid or temperature of the fluid, or both, thatis circulated to the heat exchange balloon. In this manner, the amountof heating or cooling of the blood that flows past the heat exchangeballoon may be controlled so as to accurately and efficiently controlthe heating or cooling of the target tissue or body core of the patient.

FIGS. 21A through 21C and 22A through 22C depict yet another embodimentof the present invention. This embodiment provides a system wherein atemperature probe may be deployed into a retrograde position relative toan introducer sheath, and then retracted and removed from the patient'svessel. This embodiment includes a deployment catheter 600 that may beinserted through the proximal opening (not shown) of an introducer 602,advanced through lumen 605 of introducer 602 until distal end region 610of the deployment catheter 600 extends out of and beyond distal opening607 of introducer 602. At least distal region 610 of deployment catheter600 is formed from a compressible material that has a memory such thatthe distal region has a compressed diameter that is smaller than thediameter of the lumen 605 of introducer 602, and an expanded diameterthat is larger than the diameter of the lumen 605 of introducer 602. Inone embodiment, a slot 615 may be formed in one or more areas of distalend region 610 so as to assist in compressing distal end region 610 tothe compressed diameter. As depicted in FIGS. 21A through 22C, slot 615is formed having an open side disposed at a the distal end 612 of distalend region 610, separating distal end 612 into two or more segments,depending on the number of slots formed therein. These segments, becausethey are spaced apart from one another by the open end of the slot 615,can move towards one another to provide the compressed diameter ofdistal end region 610. Alternatively, distal end region may be formedfrom a flexible material that allows the wall of distal end region 610to fold into a compressed diameter when the distal end region 610 isdisposed within lumen 605, and unfold and expand to an expanded diameterwhen distal end region 610 is advanced beyond distal opening 607 ofintroducer 602.

As shown in FIG. 21A, distal end region 610 of deployment catheter 600is advanced through lumen 605 of introducer 602. Distal end region 610also includes a guide tube 620 disposed on an inner surface of the wallof distal end region 610. Guide tube 620 includes a lumen extendingbetween a proximal opening 622 and a distal opening 623. A probe 625having a bend region 630 and a distal region 632 is disposed with alumen of the deployment catheter 600 such that the distal region 632 ofprobe 625 extends through the lumen of the guide tube 620 out of distalopening 622 of guide tube 620. A temperature sensor 635 is disposed atthe tip of distal region 632 of probe 625.

When distal end region 610 is advanced sufficiently beyond distalopening 607 of introducer 602, as depicted in FIG. 21B, distal endregion 610 expands to its expanded diameter. When distal end region 610expands to its expanded diameter, a port 640 formed in at least aportion of the proximal end of the distal end region 610 opens to form apathway between the interior lumen of distal end region 610 and the areaexterior to the introducer 602. Thus, when the system as described isused to locate a temperature probe within a vessel retrograde to thedistal opening of the introducer, port 640 provides a pathway betweenthe interior of the deployment catheter 600 and the blood stream. Onceport 640 is open, probe 625 may be pulled in a proximal direction,pulling the distal region 632 of the probe 625, and thus temperaturesensor 635, through port 640 in a retrograde direction to positiontemperature sensor 635 at a location retrograde of the distal end of theintroducer 602, as is shown in FIG. 21C. In this embodiment, bend region630 of probe 625 interacts with the distal end of the guide tube 620 tolimit the extent that temperature sensor 635 may be moved in aretrograde direction. Accordingly, the length of distal region 632 ofprobe 625 by be sized to provide a controlled positioning of temperature635 in a retrograde location relative to the distal end of theintroducer.

It will be understood that deployment catheter 600 has a central lumenthrough which the probe is advanced and removed. The central lumen ofdeployment catheter 600 has a diameter large enough to allow theadvancement and removal of other catheters, such as a heat exchangecatheter, through the lumen while the temperature sensor is deployed ina retrograde location. Moreover, port 640 in distal end region 610 alsoprovides a pathway for blood or other bodily fluid to flow through thedistal end region of the deployment catheter 600 when the distal endregion 610 is in its expanded state. This allows the expanded diameterof distal end region 610 to be as large as the inner diameter of avessel lumen without obstructing the flow of blood or other body fluidthrough the vessel.

FIGS. 22A through 22C depict the removal of the temperature probe anddeployment catheter of FIGS. 21A through 21B from a patient's vessel. Asshown in FIG. 22 b, probe 625 is advanced in a distal direction, causingtemperature sensor 635 disposed on the tip of distal region 632 to bepulled back into the interior of distal end region 610 of deploymentcatheter 600.

Once temperature sensor 635 is positioned within the interior of distalend region 610, deployment catheter 600 may be pulled toward theproximal end of introducer 602, collapsing distal end region 610 intoits compressed state, as shown in FIG. 22C. In this manner, atemperature sensor may be deployed in a retrograde location in apatient's vessel, and then removed from the vessel such that the sensoris protected during deployment and removal, and the vascular tissue isalso protected from abrasion or laceration caused that could occur ifthe probe were not protected by the deployment catheter when thetemperature sensor is deployed or removed.

While the invention has been described in connection with certaindisclosed embodiments, it is not intended to limit the scope of theinvention to the particular forms set forth, but, on the contrary it isintended to cover all such alternatives, modifications, combinations andequivalents as may be included in the spirit and scope of the inventionas defined by the appended claims.

1. A system for measuring the temperature of a body fluid flowing withina body lumen at a location upstream of the insertion of a temperatureprobe into the body lumen, comprising: a temperature probe having aproximal end, an intermediate region having a bend formed therein and adistal region, the distal region being proximal of the bend and having adistal tip with a temperature sensor mounted thereon; and a sheathadapted for insertion into a body lumen, the sheath having a proximalend and a distal end, the sheath having a central lumen having aproximal opening disposed at the proximal end of the sheath, a distalopening disposed at the distal end of the sheath and a central lumenaxis extending from the proximal opening to the distal opening, acapture tube attached to the distal end of the sheath, the capture tubehaving a distal opening adjacent the central lumen distal opening, aproximal opening, and a lumen extending therebetween, the lumen having alumen axis parallel to the central lumen axis, the lumen having alength, the length selected to receive and protect the distal tip and atleast a portion of the distal region of the temperature probe when thesheath and temperature probe are inserted into a body lumen; and whereinretracting the proximal end of the temperature probe from the sheathcauses the distal tip of the temperature probe to move in a proximaldirection, moving the distal tip out of the proximal opening of thecapture tube to a desired location proximal to the proximal opening ofthe capture tube without additional assistance.
 2. The system of claim1, wherein the proximal end of the temperature probe extends into thedistal end of the sheath and through the central lumen.